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Old 05-17-2015, 11:45 PM   #1
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Default idles fine, drops, then slowly rises

I am am beyond confused with what I need to do to get my start up idle working correctly. I tried editing the ASE and WUE but neither seem to help. Here is what is happening, hopefully someone can point me to the settings i need to adjust.

The car starts and idles at 1100 rpms when its at around 86 degrees coolant temp (this is good). The car stays at this idle as the temps rise but once it hits 92 degrees it makes a noise and drops right down to 700, sometimes even stalling. If it doesnt stall the RPMs will slowly rise, very slowly, until it gets back up to 1100 rpms and everything is jolly again.

I data loaded this issue, it is pretty long but it shows the entire cycle. If someone can please take a look and point me in the right direction I would greatly appreciate it.
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File Type: msl weird start idle.msl (3.22 MB, 93 views)
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Old 05-18-2015, 10:28 AM   #2
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No1 has any ideas? :(
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Old 05-18-2015, 12:20 PM   #3
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The target RPM is 800 - it appears that something happened to jolt it into the closed loop idle range. Why it drifted out of closed loop idle is a bit of a mystery. Can you also upload your MSQ?
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Old 05-18-2015, 12:22 PM   #4
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Sure thing, thanks for looking!
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File Type: msq Graver D.msq (110.7 KB, 71 views)
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Old 05-19-2015, 12:31 AM   #5
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Any ideas?
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Old 05-19-2015, 11:16 AM   #6
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Try the following:

1. Reduce the idle valve closed duty.

2. Decrease the PID control interval.

3. Increase the closed loop gain.
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Old 05-20-2015, 11:52 AM   #7
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Quote:
Originally Posted by Matt Cramer View Post
Try the following:

1. Reduce the idle valve closed duty.

2. Decrease the PID control interval.

3. Increase the closed loop gain.
so far all my tests say this helped a lot! My idle is way more controlled but I do have something going on I would like to know more about. It seems the my idle changes when the car hits 92 degrees and 89 degrees. The second I hit 92 the idle drops to 850 but if the car falls back to 89 the idle immediately jumps to 1200, then back to 850 when it hits 92 again. Do you think you could explain what is happening at those temps or are you not sure?

Thanks so much for getting me thtis far.

Also here are the setting i went with, are these safe? I kind of just guessed
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idles fine, drops, then slowly rises-6h5xrbc.png  
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Old 05-20-2015, 12:03 PM   #8
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your CLT idle speed targets are tied to engine CLT temps...
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Old 05-20-2015, 01:02 PM   #9
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your CLT idle speed targets are tied to engine CLT temps...
got it, looks like these settings needed to be changed since it looked like



but after changing it to this it still did the same thing at 89 and 92

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idles fine, drops, then slowly rises-12cskkq.png   idles fine, drops, then slowly rises-qwqoxsr.png  
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Old 05-25-2015, 12:57 PM   #10
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It seems you guys were a great help in fixing this problem! Sad thing is I am having another random idle issue I could really help with. The car starts up fine cold and drives fine up to operating temps. The issue I am having is if i drive in the heat for about 30+ minutes then let the car sit a bit, it fails to idle at start up. I turn the car on and it drops right down. If i rev the car the car to keep it from stalling and start moving the issue goes away in a few minutes.

Any idea where I should be looking or what I can post to help solve this issue?
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Old 05-25-2015, 02:06 PM   #11
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<p>look at your MAT Air Density table. &nbsp;youre removing TONS of fuel when the temps get warm.</p><p>My rule of thumb for that table is to set it completely to 100%. &nbsp;once your fuel table is good, then start adjusting that table to keep AFRs in check when the temps hit extremes.</p>
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Old 05-25-2015, 06:36 PM   #12
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If it's not running lean due to fuel air density compensation, you can also see if the engine needs more IACV duty. You can set your initial duty table to have manifold air temp on the y axis and make compensations there. I've had good luck adding duty with increasing air temp.

Unfortunately you can no longer compensate initial duty according to coolant temperature when you switch the table axis over.

To some extent you can tell how far off your MAT density table is by how much your closed loop fuel feedback is adjusting. If it's over 10% adjustment (for example, adding 10% fuel) then maybe it's too lean due to air compensation. That assumes the VE table was set pretty well when you initially tuned it though. A lot of these compensations can make you chase your tail if you don't get good baseline values in there.
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Old 05-27-2015, 03:28 PM   #13
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Im in the car now and it seems that only helped a little. Now the car starts to idle but when i rev it and let it drop down the car stalls... Sorry for all the questions I just am at wits end here and need to solve this.

Attached are 2 data logs. One where I start it, rev it, and it dies. Another where i start it, rev it but dont let it die. In the 2nd log you can see the car struggle to idle until it finally stabalizes.
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File Type: msl idle drop no ac.msl (206.0 KB, 68 views)
File Type: msl drop stall.msl (254.5 KB, 79 views)
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Old 05-27-2015, 03:46 PM   #14
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<p>DC% drops really low before it stalls. &nbsp;just glancing quickly at spreadsheet.</p><p>what injectors do you have?</p>
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Old 05-27-2015, 04:09 PM   #15
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Quote:
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<p>DC% drops really low before it stalls. &nbsp;just glancing quickly at spreadsheet.</p><p>what injectors do you have?</p>
RX7 Red tops 460cc. I had then cleaned and flow tested a few months ago
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Old 05-27-2015, 04:16 PM   #16
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<p>yeah if you hit 1.2ms with those injectors it will stall. &nbsp;that's essentially 0 fuel.</p>
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Old 05-27-2015, 04:21 PM   #17
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<p>yeah if you hit 1.2ms with those injectors it will stall. &nbsp;that's essentially 0 fuel.</p>
What can I do to fix this? I wish i wasnt so clueless here :/
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Old 05-27-2015, 04:37 PM   #18
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I found these 2 threads but am not knowledgeable enough to know what my next steps are.

https://www.miataturbo.net/ecus-tuni...e-56061/page5/

https://www.miataturbo.net/ecus-tuni...hen-hot-67534/

Is this what you think my issue is?
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Old 05-27-2015, 06:26 PM   #19
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Quote:
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<p>yeah if you hit 1.2ms with those injectors it will stall. &nbsp;that's essentially 0 fuel.</p>
Im using a MS2 and cant seem to find an Injector Characteristic setting. Should I try increasing the Injector Dead Time @13.2v or am I looking in the wrong place?
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Old 05-27-2015, 06:30 PM   #20
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<p>looking again, I think the DT is fine. 1.2ms is good for those injectors.</p><p>&nbsp;</p><p>what i see in the first &nbsp;log is the car running at 44% idle DC to maintain a smooth 950RPM idle.</p><p>when you blip the throttle and the car goes back to the initial duty table, it's aimin gfor 34%DC whihc is way to low for it to acheive a sustainable idle and it stalls. &nbsp;</p><p>I'd tune the intial idle duty table to values to that make sense.</p><p>I also see the idle valve nor spark react to try to hit idle, I dont like your delay settings and I would enable adaptive ignition timing so that MS uses spark angle to control idle when it gets too far off of targets.</p><p>&nbsp;</p><p>the scond log shows a VERY untuned idle valve. it's holding steady while your enginge speed ocssilates a good 250RPM.</p><p>I'd tune the idle control PID settings to values that allow the idle valve to WORK. &nbsp;Again, the delay is too long (10sec) and inital duty too low and why it's doing that initially in the log before it finally rises and stablizes.</p><p>&nbsp;</p><p>TUNE TUNE TUNE TUNE. you need to tune. &nbsp;tune the idle settings so the car idles well and doesnt stall. tune--as in tune the car.</p>
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